After making its debut with the new Xperia Z3, PS4 Remote Play is now available to all Android users (from version 4.0) by a member of XDA forum.
PlayStation 4 or PS4 Remote Play Compatible with all devices running Android 4.0 and later
It is now possible to enjoy PS4 Remote Play on Android smartphones from other brands through an USB type port, of course. Xperia Play station. This means that the installation will be done manually. The various required installation files have been made available in the dedicated server along with instructions.
There is still a constraint: the smartphone must have at least Android 4.0 or Ice Cream Sandwich. As always, with this kind of operation, be safe and remember to make a backup before you begin. Obviously we invite you to share your experience in the comments so that the compatibility can be improved with some later models.